1. Field of the Invention
The present invention relates to an electronic apparatus, and more particularly to a housing structure of an electronic apparatus. The present invention is suitable, for example, for a housing structure of a mobile radio communication phone, a personal digital assistant, and a portable game machine.
2. Description of the Related Art
Recently, a higher function and a lower profile are increasingly required for a cellular phone, and it is also important to maintain a housing strength and an electric characteristic of the cellular phone in addition to meeting these requirements. From the demand for the higher function, one proposed cellular phone has an arm that is configured to rotate relative to the fixing part, and a movable part that is mounted with the display and configured to rotate relative to the arm. A user can view the display in vertically orientation or in a lateral orientation by rotating the movable part. An arm accommodates an electronic component that is connected to a communication part, a display, and a fixing part.
On the other hand, from the demand for the lower profile demand, the housing of the cellular phone has increasingly been thinner, but the arm particularly needs to maintain a (bending) strength since a twisting force applies to the arm in rotating the movable part. While a cover member attached to a case of the conventional arm has a three-layer structure that consists of a resin layer, an adhesion layer, and a resin layer, it has been proposed to replace the outermost resin layer with a metal (or Al) layer, because the metal layer is stronger than the resin layer.
Prior art includes Japanese Patent Laid-Open No. (“JP”) 09-58164.
In the cover member of the arm that consists of the metal layer, the adhesion layer, and the resin layer, each of the metal layer and the resin layer has a U-shaped section made of a flat part that is bent at both sides, and the adhesion layer is made of a double-sided tape. While the size of the resin layer is precisely formed through injection molding, it is difficult to precisely form the metal layer having a fine curved surface. In addition, the metal layer and the resin layer have a different coefficient of thermal expansion. Hence, when the metal layer is adhered to the resin layer via the adhesion layer, the flat part of the metal layer is stretched by the flat part of the resin layer, and a warp occurs at the edge of the U-shaped section of the cover member due to a manufacturing size error and the different coefficient of thermal expansion of both members, causing the end of the metal layer to float over the resin layer. As a result, a slight gap occurs between the end of the metal layer and the resin layer. When the resin layer is provided with a perforation hole to expose part of the electronic component in order to realize a lower profile configuration, foreign particles enter the perforation hole and may deteriorate the electric characteristic through short circuiting of the electric circuit.